hey-i-get-this.cfc

    public numeric function getTotalDiscountForOrder(required array orderProducts) {
        var totalSavings = 0;
        for (var product in arguments.orderProducts) {
            totalSavings += calculateCouponDiscountForProduct(product) * product.quantity;
        }

        return totalSavings;
    }
    
    public array function addOrderProductsDiscountedPrice(required array orderProducts) {
        for (var product in argument.orderProducts) {
            product["discountedPrice"] = getProductPriceAfterDiscount(product);
        }

        return argument.orderProducts;
    }

    public numeric function getProductPriceAfterDiscount(required struct product) {
        return arguments.product.price - calculateCouponDiscountForProduct(arguments.product);
    }

    public numeric function calculateCouponDiscountForProduct(required struct product) {
        var discount = 0;
        var couponsForProduct = $getCouponsForProduct(arguments.product.id);
        for(var coupon in couponsForProduct) {
            discount += arguments.product.price * (coupon.discountpercent/100);
        }

        return discount;
    }